1. Field of the Invention
The present invention relates to an image forming apparatus such as copiers and printers, as well as to a data communication method. Particularly in an image forming apparatus including a transmitter for sequentially transmitting data, such as image data, which comprises a variety of pulse signals, and a receiving portion for receiving the data comprising the pulse signal transmitted from the transmitter, a feature of the invention resides in a data communication method which is effective to prevent the occurrence of high-level irradiation noise when the transmitter transmits the data, such as the image data, which contains a high-frequency pulse signal having a large number of On/Off shifts.
2. Description of the Related Art
The image forming apparatus such as the copiers and printers conventionally perform a variety of operations such as image formation, as follows. The transmitter transmits the data, such as the image data, comprising a variety of pulse signals. The receiving portion receives the data comprising the pulse signal and transmitted from the transmitter. The operations such as the image formation are performed based on the data comprising the pulse signal and received by the receiving portion.
Unfortunately, the image data or the like often contains the high-frequency pulse signal having a large number of On/Off shifts. In a case where the transmitter transmits such a high-frequency pulse sign a to the receiving portion via a relatively long transmission member such as a harness, the high-level radiation noise occurs so that peripheral devices are adversely affected.
As disclosed in Japanese Unexamined Patent Publication No. 2001-309174, the following image processing apparatus and method have been proposed in the art.
The apparatus and method comprises: means for generating a flag signal which is invertible between On position and Off position in junction with each multivalued image data piece;
converting means for converting the multivalued image data to density data based on the multivalued image data and the flag signal; and
means for converting the resultant density data to serial video signals.
According to the image forming apparatus and the image processing method, out of the signals comprising plural bits representing respectively generated density data pieces, on-bits are collectively raised in a timewise forward or rearward direction according to the flags whereby the number of On/Off shifts is reduced for suppressing the radiation noises.
However, the following problem is encountered in the case where out of the signals comprising the plural bits representing the respectively generated density data pieces, the on-bits are collectively raised in the timewise forward or rearward direction according to the flags. Although the general density of the image may be controlled, it is impossible to achieve a proper density control based on an image binarization method such as dither method because On/Off positions are shifted from those of the original image data. In addition, the formed images suffer feathering at edges thereof. Hence, the apparatus and method fail to provide favorable images.